20 research outputs found
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DETERGENT FRACTIONATION OF GLUTAFALDEHYDE FIXED SPINACH THYLAKDIDS
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COFACTOR EFFECTS ON ENHANCEMENT IN HADP REDUCTION BY CHLOROPLASTS
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DISTRIBUTION OF VARIABLE FLUORESCENCE AMONG SUBCHLOROPLAST FRACTIONS
Spinach chloroplasts were fragmented by the French press technique and were separated by fractional centrifugation. Variable fluorescence was assayed by adapting a Cary 14 spectrophotometer for use as a modulated detector. The amount of variable fluorescence was directly related to the abundance of Photosystem II in the fractions. The 160K fraction which possesses negligible Photosystem II activity also possesses negligible variable fluorescence. The yield of background fluorescence from the 160K fraction is also much less than that from the other fractions. The presence of inactive chlorophyll in the 160K fraction cannot be explained by damage of Photosystem II during French press fragmentation
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CHARACTERIZATION OF CHLOROPLAST PHOTOSYSTEMS 1 AND 2 SEPARATED BY A NON-DETERGENT METHOD
Class II spinach chloroplasts were fragmented by passage through the French pressure cell (French press), and the fragments were separated by fractional centrifugation. Fragments sedimenting between 1000 Ă— g and 10000 Ă— g (10K) have a lower chlorophylla/chloropyllb ratio and lower P-700 content than whole chloroplasts. Fragments sedimenting between 40000 Ă— g and 160000 Ă— g (160K) have a much higher chlorophylla/chlorophyllb ratio (6.0) and a much higher P-700 content (1 P-700 per 105 chlorophylls) than whole chloroplasts. The chlorophyll and cytochrome contents of the French press fractions are similar to those found in fractions isolated after digitonin disruption. The 160K fraction performs Photosystem 1 but not Photosystem 2 reactions. The 10K fraction contains both photosystems. Electrophoresis of sodium dodecyl sulfate solubilized 10K and 160K fractions gives further evidence for this distribution of photosystems. Thin sectioning and freeze fracturing show that the 160K fraction originates from stroma lamellae and the end membranes of grana stacks and contains only 110Ă… particles. The 10K fraction originates from the partition regions of grana stacks and contains both 110 and 175Ă… particles. This distribution of particles on fracture faces of stroma versus grana lamellae is shown to exist in freeze fractured Class I chloroplasts. These data demonstrate that both digitonin and French press treatments of chloroplasts initially break stroma lamellae and end membranes to yield small vesicles which contain only Photosystem 1
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